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Commit 6252d702 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[S390] dynamic page tables. 



Add support for different number of page table levels dependent
on the highest address used for a process. This will cause a 31 bit
process to use a two level page table instead of the four level page
table that is the default after the pud has been introduced. Likewise
a normal 64 bit process will use three levels instead of four. Only
if a process runs out of the 4 tera bytes which can be addressed with
a three level page table the fourth level is dynamically added. Then
the process can use up to 8 peta byte.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 5a216a20

arch/s390/kernel/binfmt_elf32.c

+11 −0
Original line number Diff line number Diff line
@@ -134,6 +134,7 @@ static inline int dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpregs) 
}



#include <asm/processor.h>

#include <asm/pgalloc.h>

#include <linux/module.h>

#include <linux/elfcore.h>

#include <linux/binfmts.h>
@@ -183,6 +184,16 @@ struct elf_prpsinfo32 
#undef start_thread

#define start_thread                    start_thread31 



static inline void start_thread31(struct pt_regs *regs, unsigned long new_psw,

				  unsigned long new_stackp)

{

	set_fs(USER_DS);

	regs->psw.mask	= psw_user32_bits;

	regs->psw.addr	= new_psw;

	regs->gprs[15]	= new_stackp;

	crst_table_downgrade(current->mm, 1UL << 31);

}



MODULE_DESCRIPTION("Binary format loader for compatibility with 32bit Linux for S390 binaries,"

                   " Copyright 2000 IBM Corporation"); 

MODULE_AUTHOR("Gerhard Tonn <ton@de.ibm.com>");

arch/s390/kernel/traps.c

+2 −1
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ int sysctl_userprocess_debug = 0; 
extern pgm_check_handler_t do_protection_exception;

extern pgm_check_handler_t do_dat_exception;

extern pgm_check_handler_t do_monitor_call;

extern pgm_check_handler_t do_asce_exception;



#define stack_pointer ({ void **sp; asm("la %0,0(15)" : "=&d" (sp)); sp; })
@@ -730,7 +731,7 @@ void __init trap_init(void) 
        pgm_check_table[0x12] = &translation_exception;

        pgm_check_table[0x13] = &special_op_exception;

#ifdef CONFIG_64BIT

        pgm_check_table[0x38] = &do_dat_exception;

	pgm_check_table[0x38] = &do_asce_exception;

	pgm_check_table[0x39] = &do_dat_exception;

	pgm_check_table[0x3A] = &do_dat_exception;

        pgm_check_table[0x3B] = &do_dat_exception;

arch/s390/mm/fault.c

+40 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 
#include <asm/system.h>

#include <asm/pgtable.h>

#include <asm/s390_ext.h>

#include <asm/mmu_context.h>



#ifndef CONFIG_64BIT

#define __FAIL_ADDR_MASK 0x7ffff000
@@ -444,6 +445,45 @@ void __kprobes do_dat_exception(struct pt_regs *regs, unsigned long error_code) 
	do_exception(regs, error_code & 0xff, 0);

}



#ifdef CONFIG_64BIT

void __kprobes do_asce_exception(struct pt_regs *regs, unsigned long error_code)

{

	struct mm_struct *mm;

	struct vm_area_struct *vma;

	unsigned long address;

	int space;



	mm = current->mm;

	address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK;

	space = check_space(current);



	if (unlikely(space == 0 || in_atomic() || !mm))

		goto no_context;



	local_irq_enable();



	down_read(&mm->mmap_sem);

	vma = find_vma(mm, address);

	up_read(&mm->mmap_sem);



	if (vma) {

		update_mm(mm, current);

		return;

	}



	/* User mode accesses just cause a SIGSEGV */

	if (regs->psw.mask & PSW_MASK_PSTATE) {

		current->thread.prot_addr = address;

		current->thread.trap_no = error_code;

		do_sigsegv(regs, error_code, SEGV_MAPERR, address);

		return;

	}



no_context:

	do_no_context(regs, error_code, address);

}

#endif



#ifdef CONFIG_PFAULT 

/*

 * 'pfault' pseudo page faults routines.

arch/s390/mm/init.c

+3 −2
Original line number Diff line number Diff line
@@ -112,8 +112,9 @@ void __init paging_init(void) 
	init_mm.pgd = swapper_pg_dir;

	S390_lowcore.kernel_asce = __pa(init_mm.pgd) & PAGE_MASK;

#ifdef CONFIG_64BIT

	S390_lowcore.kernel_asce |= _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH;

	pgd_type = _REGION2_ENTRY_EMPTY;

	/* A three level page table (4TB) is enough for the kernel space. */

	S390_lowcore.kernel_asce |= _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH;

	pgd_type = _REGION3_ENTRY_EMPTY;

#else

	S390_lowcore.kernel_asce |= _ASCE_TABLE_LENGTH;

	pgd_type = _SEGMENT_ENTRY_EMPTY;

arch/s390/mm/mmap.c

+65 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <linux/personality.h>

#include <linux/mm.h>

#include <linux/module.h>

#include <asm/pgalloc.h>



/*

 * Top of mmap area (just below the process stack).
@@ -62,6 +63,8 @@ static inline int mmap_is_legacy(void) 
	    current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY;

}



#ifndef CONFIG_64BIT



/*

 * This function, called very early during the creation of a new

 * process VM image, sets up which VM layout function to use:
@@ -84,3 +87,65 @@ void arch_pick_mmap_layout(struct mm_struct *mm) 
}

EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);



#else



static unsigned long

s390_get_unmapped_area(struct file *filp, unsigned long addr,

		unsigned long len, unsigned long pgoff, unsigned long flags)

{

	struct mm_struct *mm = current->mm;

	int rc;



	addr = arch_get_unmapped_area(filp, addr, len, pgoff, flags);

	if (addr & ~PAGE_MASK)

		return addr;

	if (unlikely(mm->context.asce_limit < addr + len)) {

		rc = crst_table_upgrade(mm, addr + len);

		if (rc)

			return (unsigned long) rc;

	}

	return addr;

}



static unsigned long

s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,

			  const unsigned long len, const unsigned long pgoff,

			  const unsigned long flags)

{

	struct mm_struct *mm = current->mm;

	unsigned long addr = addr0;

	int rc;



	addr = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);

	if (addr & ~PAGE_MASK)

		return addr;

	if (unlikely(mm->context.asce_limit < addr + len)) {

		rc = crst_table_upgrade(mm, addr + len);

		if (rc)

			return (unsigned long) rc;

	}

	return addr;

}

/*

 * This function, called very early during the creation of a new

 * process VM image, sets up which VM layout function to use:

 */

void arch_pick_mmap_layout(struct mm_struct *mm)

{

	/*

	 * Fall back to the standard layout if the personality

	 * bit is set, or if the expected stack growth is unlimited:

	 */

	if (mmap_is_legacy()) {

		mm->mmap_base = TASK_UNMAPPED_BASE;

		mm->get_unmapped_area = s390_get_unmapped_area;

		mm->unmap_area = arch_unmap_area;

	} else {

		mm->mmap_base = mmap_base();

		mm->get_unmapped_area = s390_get_unmapped_area_topdown;

		mm->unmap_area = arch_unmap_area_topdown;

	}

}

EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);



#endif